In an information recording/reproducing apparatus for recording information onto an information recording medium, such as an optical disc, for example, the optimum laser power of laser light used in a recording operation, for example, is set by an OPC (Optimum. Power Calibration) process, depending on the type of the optical disc, the type of the information recording/reproducing apparatus, recording speed and so on. That is, the calibration for the laser power is performed. By this, it is possible to realize an appropriate recording operation. For example, if the optical disc is loaded and a writing command is inputted, data for test writing is recorded into an OPC area, with sequentially changing the light intensity. A so-called test writing process is performed. Then, the data for test writing recorded in this manner is reproduced, and this reproduction result is judged by a predetermined estimation standard, to thereby set the optimum laser power.
On the other hand, there is also developed a technology of increasing the recording speed (or reproduction speed) of the information by increasing the rotational speed of the optical disc. For example, in a CD-ROM as one example of the optical disc, efforts are made to speed up the recording speed of data, such as 24 times speed and 48 times speed, with a higher rotational speed of the optical disc.    Patent document 1: Patent publication No. 3159454